CN106362678A - Preparation method of water body molybdate adsorbent on basis of solid waste coal cinders - Google Patents

Abstract

The invention discloses a preparation method of a water body molybdate adsorbent based on solid waste coal slag, and belongs to the field of water body pollutant adsorption materials. The preparation method specifically includes the following steps: (1) Grinding, rinsing, and drying the cinders naturally; (2) modifying the obtained solid after particle size screening, and performing sulfuric acid, lanthanum chloride, and hexadecane respectively (3) washing with deionized water and drying to obtain La-CTMAB modified coal slag adsorption material. After the surface sewage with a molybdate concentration of 5 mg/L is treated by the adsorption material of the present invention, the molybdate content of the water body reaches the groundwater quality standard (GB/T 14848-9) category IV (≤0.5 mg/L). The invention has the characteristics of low cost, high adsorption efficiency, wide application, etc., not only realizes resource utilization of waste, but also brings good social and economic benefits.

Description

A kind of preparation method of water body molybdate adsorbent based on solid waste cinder

technical field

The invention belongs to the field of adsorption materials for water body pollutants, and in particular relates to the preparation of a molybdate sewage treatment adsorption material, in particular to a composite adsorption material based on solid waste and a preparation method thereof.

Background technique

Molybdenum is one of the trace elements necessary for the survival of animals and plants, and it is also an important strategic resource in the development of the national economy. The chemical form of heavy metal molybdenum is variable, and it usually exists in two oxide forms in nature, one is tetravalent molybdenum, and the other is hexavalent molybdenum. In acidic environments, molybdates are easily concentrated and immobilized, while in alkaline and oxidizing environments, molybdates are re-released into the environment. Due to relatively backward molybdenum mining technology and insufficient management of alkaline molybdenum tailings, molybdenum pollution in water bodies in some areas is relatively serious. Molybdenum exceeding the standard will not only cause serious harm to the human body, such as headache, gout syndrome, arteriosclerosis and other symptoms, but also have obvious toxic effects on animals and plants. For this reason, my country has made strict requirements on the concentration of molybdenum in groundwater and drinking water respectively. The concentration of molybdenum in category IV of groundwater is ≤0.5mg/L, and the concentration of molybdenum in drinking water is less than 0.07mg/L. How to remove molybdate in water efficiently and at low cost, and solve the heavy metal molybdenum pollution of surface water in surrounding areas caused by molybdenum tailings drainage has become one of the current key research directions for water environmental pollution prevention and control.

The current removal methods for molybdate sewage mainly include chemical precipitation, ion exchange, membrane filtration, and adsorption. The chemical precipitation method is prone to secondary pollution. Ion exchange and membrane filtration usually require high operation and maintenance costs, and the later operation is difficult. Therefore, the use of adsorption to remove molybdate in sewage has very broad application prospects. Inorganic and organic materials commonly used as adsorbents are often difficult to meet the requirements of environmental friendliness. For example, the ceramsite carrier in the inorganic adsorption material will require a large amount of clay in the preparation process, which not only conflicts with the current tight production land, but also consumes a lot of energy during the sintering preparation process; while the organic adsorption material usually comes from petroleum derivatives. is a non-renewable resource.

In the research technology of adsorbent materials, there are some technologies that use coal cinder to prepare adsorbent materials, but they are mainly used in gas adsorbents. For example, Chinese patent application number 201410358609.6, the application publication date is October 1, 2014. This patent discloses a patent document titled "A Formaldehyde Adsorbent for Surface Modification of Modified Coal Slag"; Chinese Patent Application No. 201410358632.5, the application publication date is July 26, 2014. The patent discloses a patent document titled "A modified coal-fired slag with high-efficiency adsorption of ammonia and its preparation method". There are also related patents on the technology of using cinder modified as heavy metal adsorbent, such as Chinese patent application number 201510452239.7, the application publication date is November 18, 2015. The patent discloses a patent document titled "A Preparation Method of Waste-Based Heavy Metal Ion Adsorbent". The preparation of the adsorbent is to add tobacco straw waste to the activated sludge of urban sewage treatment plant, heat and carbonize to obtain a high-temperature carbonized solid product; then add tobacco straw waste to coal cinder, add pickling wastewater, and configure it into a mixed Slurry: the high-temperature carbonized solid product is directly added to the mixed slurry after it is released from the furnace, and then microwaved while stirring; then it can be obtained by cooling, drying and pulverizing in sequence. The preparation process of the adsorption material is complex, and it is mainly aimed at heavy metal cations in electroplating sewage, and is not suitable for the adsorption of molybdate in anion state.

In the molybdate adsorption research technology, there are also related patents. For example, Chinese Patent Application No. 201310291466.7, published on January 14, 2015, published a patent document titled "A Method for Removing Hexavalent Molybdenum in Water"; Chinese Patent Application No. 201210212913.0, published on 2012 On October 3, 2011, a patent application document titled "A Treatment Method for Molybdenum-Containing Acidic Wastewater Produced During the Production of Ammonium Molybdate" was disclosed, as well as the Chinese patent number: 200710179661.5, and the authorized announcement date was September 2011 On the 21st, the public title was "A Treatment Method for Molybdenum-Containing Acidic Wastewater". However, the processing and operation costs of the above-mentioned technologies are relatively high, and the operation process is complicated.

Contents of the invention

Aiming at the disadvantages of high operating cost, difficult operation and easy secondary pollution in the existing technology for removing molybdate from water, the present invention provides a method for preparing water molybdate adsorbent based on solid waste cinder, In order to achieve the purpose of simple preparation process and low operating cost, the adsorption capacity of molybdate is improved, and an effective way for waste resource utilization is also provided.

In order to solve the above problems, the present invention adopts the following technical solutions.

A kind of preparation method of the water body molybdate adsorbent based on solid waste coal slag of the present invention specifically comprises the following steps:

(1) Put the coal cinder into clear water and wash it for 2 days, then grind it, rinse it, dry it naturally, and screen to obtain the coal cinder with a particle size below 0.15 mm;

(2) Add 2.0-4.0mol/L H ₂ SO ₄ solution to the above cinder, vibrate for 8-10 hours at a vibration speed of 200r/min, then wash with water until no SO ₄ ^2- is contained, and air dry for later use;

(3) Put the solid obtained in step (2) into a 500mL conical flask, add 200mL of 0.01-0.03mol/L LaCl ₃ ·6H ₂ O solution, seal the conical flask and place it at 30-35°C In a constant temperature oscillator, shake at a speed of 150-200r/min for 2-4h, filter and collect to obtain solid materials;

(4) Add the solid material obtained in step (3) to the CTMAB solution of 0.02-0.04mol/L, vibrate in a water bath at 25-45°C for 12-15h, filter and wash with deionized water until neutral, and The solid material is dried in an oven at 80-100° C. to obtain the La-CTMAB modified coal slag adsorption material, that is, the water body molybdate adsorbent.

The solid waste-based adsorption material of the present invention is obtained by acidifying coal slag, loading metal lanthanum and grafting functional groups. The present invention utilizes that the coal slag itself is a porous solid with a large specific surface area, and after it is modified, the water body molybdate is adsorbed. The specific principle is speculated as follows:

When the pH value is 2.0-7.0, the groups on the surface of lanthanum hydroxide in La-CTMAB modified cinder mainly exist in the form of La-OH ₂ ⁺ and La-OH, and the surface of lanthanum hydroxide is generally positively charged; while when the pH value When the temperature is 7.0-11.0, the groups on the surface of lanthanum hydroxide in La-CTMAB modified coal slag mainly exist in the form of La ^- OH and La-O-, and the surface of lanthanum hydroxide is generally negatively charged. At the same time, after being modified by CTMAB, the ammonium terminal of CTMAB itself undergoes ion exchange with Ca ²⁺ and Mg ²⁺ in coal slag itself, thereby introducing carbon long chain molecules of cationic surfactants. More hydrophobic active sites can better adsorb lanthanum particles on the surface.

The existence form of molybdate in water is very complex, and it is easily affected by pH. When the pH is 2.0-4.6, the main forms of molybdate ions are Mo ₇ O ₂₁ (OH) ₃ ^3- , Mo ₇ O ₂₂ (OH) ₂ ^4- , Mo ₇ O ₂₃ (OH) ^5- , Mo ₇ O ₂₄ ^6- . After the reaction system was acid-adjusted with dilute sulfuric acid, the La-CTMAB modified coal slag had a strong complexation effect on molybdate (as shown in formula 1), and at the same time, the molybdate anion and the positively charged La-OH ₂ ⁺ Electrostatic attraction (as shown in formula 2) will occur in the solution, which promotes the comprehensive adsorption capacity of La-CTMAB modified coal slag to molybdate ions, thereby achieving the purpose of removing molybdate from water.

S-La-OH+Mo _x O _y ^z- → S-La-Mo _x O _y ^z- +OH ^- (1)

S-La-OH ₂ ⁺ +Mo _x O _y ^z- → S-La-OH ₂ ⁺ -Mo _x O _y ^z- (2)

Among them, S is the surface of the adsorption material, and Mo _x O _y ^z- is the polymorphic molybdate ion.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The La-CTMAB modified cinder prepared by the present invention has certain pore structure and surface chemical characteristics, and has a high adsorption rate of molybdate in water (when the Mo concentration is 5.0mg/L, the removal rate is as high as more than 90%). After the surface sewage with a molybdate concentration of 5 mg/L is treated by the adsorption material of the present invention, the molybdate content of the water body reaches the groundwater quality standard (GB/T 14848-9) category IV (≤0.5 mg/L).

(2) The waste solid used in the present invention is cinder, and the adsorption raw material is a common solid waste in the coal industry, which has a wide range of sources and is cheap. At the same time, cinder itself has a certain mechanical strength, thus expanding its application range as an adsorption material;

(3) The adsorbed saturated material can be reused as molybdenum adsorption material after backwashing, and the eluted molybdenum can be further utilized after recycling. The invention not only realizes resource utilization of waste, but also brings good social and economic benefits.

Description of drawings

Figure 1 is a schematic diagram of the preparation process of the present invention.

Fig. 2 is the scanning electron micrograph before La-CTMAB modified coal slag adsorption in the embodiment of the present invention 1;

It can be seen from the figure that the surface structure before adsorption is looser and has more voids, which is mainly due to the insertion of lanthanum ions and CTMAB between the raw material layers.

Fig. 3 is the scanning electron micrograph after La-CTMAB modified coal slag adsorption molybdate ion in the embodiment of the present invention 1;

It can be seen from the figure that compared with the surface of the material before adsorption, the surface of the material after adsorption of molybdate ions is denser.

Fig. 4 is the curvilinear figure (experimental condition is: tested Mo concentration is 5mg/L; Adsorption temperature is 25 ℃ for solution pH to the adsorbent material prepared by the embodiment of the present invention 1 to remove molybdate ion; Adsorbent material is 0.1g, molybdenum solution 50mL);

It can be seen from the figure that the adsorption process is greatly affected by the environmental acid-base conditions, and the adsorption efficiency is higher under acidic conditions.

Fig. 5 is the adsorption isotherm of La-CTMAB modified coal slag to molybdate ion in the embodiment 1 of the present invention (experimental condition is: adsorption temperature is 25 ℃; Solution system pH is 3.0; Adsorption material is 0.1g, molybdenum solution 50mL) ;

It can be seen from the figure that as the equilibrium concentration of molybdenum increases, the adsorption amount of the material increases gradually and tends to be constant.

detailed description

The present invention will be described in further detail in conjunction with the accompanying drawings, but not as a limitation of the present invention.

Example 1

Put the coal cinders into clean water and rinse for 2 days, then grind, rinse, dry naturally, and screen to obtain 20 g of coal cinders with a particle size of 0.15 mm or less. Add 50 mL of 2.0 mol/L H ₂ SO ₄ solution to the above cinder, shake for 10 hours at a vibration speed of 200 r/min, then wash with water until no SO ₄ ^2- is contained, and air-dry for later use; take 10 g of the above solid and put it into 500 mL Add 200mL of 0.01mol/L LaCl ₃ 6H ₂ O solution to the conical flask, seal the conical flask and place it in a constant temperature shaker at 35°C, vibrate at a speed of 200r/min for 2h, filter and collect the solid Material: Add the solid material to 200mL of 0.02mol/L CTMAB solution, shake in a water bath at 25°C for 13h, filter and wash with deionized water until neutral, and place the solid material in an oven at 100°C to dry dry, that is La-CTMAB modified cinder 1.

Example 2

Put the coal cinders into clean water and rinse for 2 days, then grind, rinse, dry naturally, and screen to obtain 20 g of coal cinders with a particle size of 0.15 mm or less. Add 50 mL of 4.0 mol/L H ₂ SO ₄ solution to the above cinder, shake for 8 hours at a vibration speed of 200 r/min, then wash with water until no SO ₄ ^2- is contained, and air-dry for later use; take 10 g of the above solid and put it into a 500 mL Add 200mL of 0.01mol/L LaCl ₃ ·6H ₂ O solution to the Erlenmeyer flask, seal the Erlenmeyer flask, place it in a constant temperature shaker at 35°C, vibrate at a speed of 200r/min for 2h, filter and collect the solid material ; Add the solid material to 200mL of 0.03mol/L CTMAB solution, shake in a water bath at 30°C for 12h, filter and wash with deionized water until neutral, and dry the solid material in an oven at 100°C , which is La-CTMAB modified cinder 2.

Example 3

Put the coal cinders into clean water and rinse for 2 days, then grind, rinse, dry naturally, and screen to obtain 20 g of coal cinders with a particle size of 0.15 mm or less. Add 50 mL of 4.0 mol/L H ₂ SO ₄ solution to the above cinder, shake for 8 hours at a vibration speed of 200 r/min, then wash with water until SO ₄ ^2- is not contained, and air-dry for later use; put the obtained solid into 500 mL Add 200mL of 0.03mol/L LaCl ₃ 6H ₂ O solution to the conical flask, seal the conical flask and place it in a constant temperature shaker at 35°C, vibrate at a speed of 200r/min for 2h, filter and collect the solid Material: Add the solid material to 200mL of 0.04mol/L CTMAB solution, shake in a water bath at 45°C for 15h, filter and wash with deionized water until neutral, and place the solid material in an oven at 100°C to dry Dry, that is La-CTMAB modified cinder 3.

Example 4

Same as Example 3, the difference is that 2.0 mol/L H ₂ SO ₄ solution is added to the coal slag, and shaken for 10 h.

Example 5

Same as Example 3, except that the Erlenmeyer flask was sealed and placed in a constant temperature shaker at 30°C, and shaken at a speed of 200r/min for 4h.

comparative example

Put the coal cinders into clean water and wash them for 2 days, then grind them, rinse them, dry them naturally, and screen them to get coal cinders with a particle size below 0.15mm, which will be directly used as molybdenum adsorption materials.

The coal slag adsorption materials prepared in the above-mentioned Examples 1-5 and Comparative Examples were respectively subjected to molybdenum removal adsorption tests, and the experimental water was self-mixed molybdenum sewage with sodium molybdate (Na ₂ MoO ₄ ), and its Mo(VI) concentration was 5.0 mg/L. The adsorption material is 0.1g, the molybdate solution is 50mL, the adsorption time is 10h, the pH of the solution is adjusted to 3.0 with dilute sulfuric acid, the water temperature is 25°C, and the oscillation speed is 150r/min.

Test data shows that the adsorption material obtained in Examples 1-5 of the present invention has a very significant removal efficiency for molybdate in sewage (as shown in Table 1). When the concentration of molybdate was 5.0 mg/L, the removal rate of molybdenum by the adsorption materials 1-5 was significantly higher than that of the comparison adsorption materials.

Table 1 Different embodiment removes molybdenum experimental result

Example 1 Example 2 Example 3 Example 4 Example 5 comparative example Mo equilibrium concentration (mg/L) 0.33 0.29 0.16 0.25 0.18 1.82 Removal rate (%) 93.40 94.20 96.80 95.00 96.40 63.60

Claims (1)

1. a kind of preparation method of the water body molybdate adsorbent based on solid waste cinder is it is characterised in that include following walking Rapid:

(1) cinder is put into and in clear water, washes away 2d, carry out afterwards grinding, rinse, spontaneously dry, screening obtain particle diameter 0.15mm with Under cinder；

(2) by the h of 2.0-4.0mol/l₂so₄Solution is added to above-mentioned cinder, vibrates 8-10h, and vibration velocity is 200r/min, uses afterwards Water washing is to no longer containing so₄ ^2-, air-dry standby；

(3) solid obtaining step (2) is put in conical flask, and adds the lacl of 0.01-0.03mol/l₃·6h₂O is molten Liquid, is placed in after conical flask is sealed in 30-35 DEG C of constant temperature oscillator, with the velocity fluctuation 2-4h of 150-200r/min, filters simultaneously Collection obtains solid material；

(4) solid material obtaining step (3) is added in the ctmab solution of 0.02-0.04mol/l, in 25-45 DEG C of water-bath Middle vibration 12-15h, is washed with deionized to neutrality after filtration, and this solid material is placed in baking in 80-100 DEG C of baking oven Dry, obtain la-ctmab modified coal slag adsorbing material.